A name for the mountain range that ran in a great arc for some six hundred miles from the far northern parts of Middle-earth southward as far as Fangorn Forest. The name 'Towers of Mist' is a rare old form, and a slightly more direct translation of the Elvish name for this range, Hithaeglir (hith means 'mist', while aeglir comes from the word for a mountain range, especially one made up of sheer and pointed peaks).

Historically the Towers of Mist had been even sharper and more impassable than they later became. They were originally raised by the Dark Lord Melkor to hinder the ridings of the Vala Oromë in Middle-earth. In this they failed, as Oromë was able to make his way into the eastern lands and discover the newly awakened Elves. Even in the Third Age, the mountains remained a nearly impassable barrier, with only a handful of dangerous passes crossing the mountains from west to east.